public function testContains()
{
$elements = [1, 'A' => 'a', 2, 'null' => null, 3, 'A2' => 'a', 'zero' => 0];
$collection = new ArrayCollection($elements);
$this->assertTrue($collection->contains(0), 'Contains Zero');
$this->assertTrue($collection->contains('a'), 'Contains "a"');
$this->assertTrue($collection->contains(null), 'Contains Null');
$this->assertFalse($collection->contains('non-existent'), "Doesn't contain an element");
}
